How to break through to the next level? (1600-1700)

Yeah, for certain ratings I think the main question is what haven't you studied yet?
Openings, strategy, tactics, endgames. Pick one. Probably the one you'd rather not pick
Get a good book on it, and study every single page of it. Take notes. Review the notes.
That's how I improved every time I've improved.
Later it might be something like, wow, I really suck at attacking. Or IQP positions, or rook endgames, etc. Ok, then it's probably a topic you've been avoiding because you don't like it for one reason or another. Focus completely on it, and you'll improve.
The neat thing is it will help in unexpected ways. For me, when I studied endgames, they put such a high importance on piece activity that it helped me solve tactic puzzles more efficiently.
Or, I dig into IQP positions, then later when looking at my opening repertoire, instead of running away from IQP positions I look forward to playing them, so I'm willing to go into more main lines. Stuff like that.

It's not realistic to expect bleeding-edge innovation, and objectivity too.
So some parts of the books are a bit over-blown.
When you read the books with that perspective in mind, they become both more readable and more entertaining.
Well... at least that's honest. Even with that in mind I'm not sure this would mean I would like them better haha
But ok, maybe Kmoch has more detail / information.


I wonder how far one can get in chess without reading a single book.

Don’t listen to makehelltal. Opening study is almost worthless. Unless it involves studying the Alapin variation of the Sicilian
What's special about the Alapin?


I experimented a bit, and found the best daily practice routine to achieve your desired rating. (I recommend practicing chess in the morning before lunch, as that is when we are most productive.)
Firstly, take about at least an hour in the morning to do ONLY puzzles, and puzzle rush. Then at the end of the day, play a couple UN-RATED online games, then play 1 Rated game. If you win, you get to rest and do other stuff, if you lose, punish yourself by doing another hour of puzzles and puzzle rush in the afternoon.
Now Do this for 7 days, or until you start winning more consistently.
after around a week, gradually start playing more and more online rated games, and you will see your elo skyrocket. Be patient, as it will take a few days of playing to notice your elo get higher.
I tried all this by myself when i was stuck at 1600. after this training routine, my elo got up to almost 1800!!
Good luck my friend.
I think its hard to be critical about your own games, but I think one of the key things you need to do, to up your game over a rating hurdle (in particular), is to look back over your games and note why you win, and why you lose; spot a pattern in your play. Only your own games will tell you where you are struggling. Whenever you lose a game, you should always look back and know why.
Sometimes its a poor opening choice (eg. I played a lot of gambits/off-beat/irregular openings early on), other times it's simply not knowing the middle-game plans (eg. not knowing which pieces to trade/not trade, pawn breaks etc). Then there are the more specific notes - unknown mating patterns; unknown endgame technique; hanging pieces; missed combinations; failure to castle; over-reaching in an attack; slow moves in a critical position; and so on...
I just had a look back (and reminisce) at my games, around that rating barrier; whilst it might not be applicable in general - I've included some pointers for blitz at ~1600. I was still regularly hanging pieces. I was significantly mismanaging the clock. I didn't have a retort to certain lines of the Sicilian and other sharp openings. I regularly failed to get out of the opening. I over-eagerly sacrificed material for unsound attacks. I didn't get how to hold common rook endgames. Addressing those, for instance by looking at endgame & opening lectures on YT, helped me break through.
Hope that helps, and good luck on breaking into the 1600-1700 range!